Jsheet-metal tube



(MOd6L) W. G. SPENCER.

SHEET METAL TUBE.

Patented Aug. 23', 1881.

WITNESSES l hu uher. Washmpnm B. C

UNITED Srnrns ATENT Fries.

TILL-1AM Gr. SPENCER, OF BOSTON, MASSACHUSETTS.

iSHEET-METAL TUBE.

SPECIFICATION forming part of Letters Patent No. 246,232, dated August 23, 1881.

Application filed February 25, 1881.

To all whom it may concern:

Be it known that I, WILLIAM G. SPENCER, of Boston, in the county of Suffolk and State of Massachusetts, have invented an Improvement in Sheet-Metal Tubing, of which the following is a full, clear, and exact description, reference beinghad to the accompanying drawings, making part of this specification, in which- Figure l is a perspective view of a piece of sheet-metal tubing having its joint or seam made in accordance with my invention. Fig. 2 is an enlarged section taken on the line of the seam. Fig. 3 is atransverse section on the line w or of Fig. 1.

spirally-wound sheet-metal tubing has been made in which one edge of the strip was provided with tongues or projections formed by punching and striking up the metal at suitable intervals, the other edge of the strip having slits or apertures through which the tongues were passed as one edge of the strip overlapped the otherin the operation of winding it spirally around the mandrel, these tongues having been clinched or flattened down on the outside of the seam in such a manner as to hold the edges of the strip firmly together. This method answered a good purpose; but the tongues were liable to brealroff in bending orflatteningthem downif the metal was not of a best quality, thus preventing the use of a cheaper grade of metal equally as good for all the ordinary requirements of a sheet-metal tube, but not possessing the necessary toughness and capability of being bent to any considerable extent without cracking or breaking.

My invention has for its object to enable me to dispense with these tongues forming a part of the strip itself, and to employ a cheaper grade of metal, the fastening device instead of being of the same piece with the strip being composed of a separate piece or pieces of metal, which can thus be of such quality as will admit of its being bent without liability of cracking or breaking; and my invention consists in punching up the edges of the metal with a series of depressions and slits or apertures so formed that when the edges to be united are brought together the apertures will be in line, so that a piece of round or fiat wire (M0del.)

may be pushed through two or more of them in each of the contiguous edges of the metal, after which the seam so made and the fastening-wire are flattened down by suitable means, whereby the edges of the metal are held firmly together and a tightjoint insured.

In the drawings, A represents a strip of sheet metal of the required width, which as it is fed through a machine adapted for the purpose is wound spirally around a mandrel-or former. The edges to b of this strip A as it passes through the machine and before it is wound on the mandrel are acted upon by suitable mechanism in such a'manner as to form at suitable distances apart depressions c and slits or apertures d at the ends of these depressions, and as one edge of the strip is brought down onto and overlaps the other edge, as seen in Figs. 1 and 2, in the operation of winding the strip on the mandrel, the projections 6 on the under side of the edge a, produced by making the depressions c on its upper side, are brought successively over and caused to enter the depressions c on the upper side of the edge I) of the strip, which causes the slits or apertures d at the opposite ends of the depression in the edge a to be brought opposite to or in line with the corresponding slits or apertures (Z in the edge I) in such a manner as to admit of the passage of a piece of round or fiat wire, 6, (preferably annealed,) which is pushed through these apertures by suitable means, and thus serves as aloeking device for fastening the edges of the strip firmly together. A pressure-roll or other suitable device now passes over the seam and flattens down the edges of the strip and the fastening or looking wires 6, as seen in Fig. 1, which completes the operation, the two edges of the strip being held firmly and securely together by the locking-wires e, which thus form a cheap, simple, and effective fastening, the several operations of winding the strip, forming the depressions and apertures in its edges, inserting the fastening-wires, and flattening them down with the seam being all performed during a single passage of the strip through a machine adapted for the purpose; and it will thus be seen that as the fastening or locking device is separate from the strip of metal it can be made of such quality or description of metal as will admit of its being bent or clinched without any liability of cracking or breaking, thus adding materially to the integrity and strength of the joint, while the metal of which the strip itself is composed maybe of anysuitable grade or quality possessing the requirements necessary for a good tube without regard to its capability of being bent withoutliability of cracking or breaking, thus enabling me to eheapen the manufacture without impairing the eificiency or durability of the tube.

Sheet-metal tubing constructed as above described is well adapted fora great variety of purposes, and may be galvanized or tinned, if desired, to render the seam or joint perfectly tight.

hat I claim as my invention, and desire to secure by Letters Patent, is-- A spirally-wound sheet-metal tube in which the edges to I) of the strip A are provided with depressions 0, having slits or apertures d at the opposite ends thereof, and held or fast ened together by means of locking-wires 0 passed through said apertures when brought into line with each other as one edge of the strip overlaps and is pressed down upon the other in the operation of winding the strip, the seam and locking-wires being afterward flattened down to complete the joint, substantially as described.

Witness my hand this 23d day of February, A. D. 1881.

WILLIAM G. SPENCER.

In presence of- P. E. Tnscnmmonnn, WILLIAM J. CAMBRIDGE. 

